Project Summary/Abstract Associations between chronic ethanol consumption and cardiovascular diseases have been firmly established. It is well known that chronic moderate-to-heavy drinking induces arterial hypertension. This effect is of particular importance as hypertension is the single most important risk factor for global burden of disease and significant percentages of hypertension can be attributed to ethanol consumption. Only few studies have investigated mechanisms underlying ethanol-induced hypertension, which suggested that ethanol-induced hypertension is accompanied by enhanced vascular reactivity upon vasopressor exposure. A detailed understanding of these effects is lacking and the molecular mechanisms leading to sensitization of vascular function by ethanol remain elusive. The overall goals of this proposal are to determine how ethanol influences intrinsic vascular function and to identify the underlying molecular mechanisms. Our previous work and new preliminary data suggest that ethanol increases the formation of heteromeric complexes between ?1-adrenergic receptors (AR) and chemokine receptor CXCR4 within the plasma membrane, which enhances ?1-AR reactivity of vascular smooth muscle cells (VSMC) and sensitizes the intrinsic vasoconstrictor response of mesenteric resistance arteries. This leads to the main hypothesis that ethanol sensitizes intrinsic vascular function through modulation of receptor heteromerization within the plasma membrane. To test this hypothesis, we propose the following specific aims: 1. To determine the effects of ethanol on intrinsic vascular function. Utilizing pressure myography as a test platform to assess intrinsic vascular function, we will answer the following key questions: How is ?1-AR function altered in animals with arterial hypertension induced by ethanol consumption? Do metabolites of ethanol affect intrinsic vascular function? Does ethanol affect myogenic tone? Are the effects of ethanol on vascular reactivity specific for ?1-AR activation? Are there differences among vascular beds? Does the endothelium contribute to the observed effects? 2. To identify the mechanism by which ethanol sensitizes intrinsic vascular function. In this aim, we will utilize proximity ligation assays to analyze the effects of ethanol and its metabolites on the formation of heteromeric receptor complexes of ?1-AR subtypes in VSMC. Measurements of downstream signaling events will be used as read-outs for ethanol-induced effects on ?1-AR function. Furthermore, we will explore whether ethanol-induced effects on vascular smooth muscle function can be antagonized by targeting ?1-AR heteromeric complexes. Pharmacological and molecular biology approaches to interfere with receptor heteromerization will be used to establish cause-effect relationships. We propose a series of mechanistic in vitro and in vivo studies, which will provide initial information on a new molecular mechanism by which ethanol modulates control of vascular tone. This knowledge could lead to a paradigm shift in the understanding of ethanol-induced effects on vascular function and provide the starting point for the development of new and improved treatment strategies to attenuate cardiovascular risks associated with ethanol consumption.